A method is known for determining the instant of switching of a system for active thermoregulation of a resonator length of a frequency stabilized laser (Toshiko YOSHIKO, Frequency Stabilization of Internal Mirror HeNe (.lambda.=633 nm) Laser Using the Polarization Journal of Applied Physics, 19, 11, 1980, pp. 2181-2185) in which the moment of switching of a system for active thermoregulation of resonator length of a frequency stabilized laser is determined after the experimentally optimized time elapsed after the moment of the initial switching.
A disadvantage of the known method for determining the moment of switching of the system for active thermoregulation of the resonator length of frequency stabilized lasers is that it reduces the reproducibility of the frequency of laser radiation and it diminishes the admissible change in ambient temperature after initial conditions of stabilization are established, because it does not take into consideration the change of temperature and the air convection at the working site during the laser initialization regime.
A method is also known for determining the moment of switching of the system for active thermoregulation of the resonator length for a frequency stabilized laser (SORO-FRANCE, Metrilas M., 100 IE--Manuel d'utilisation et de Maintenance, 1976), in which after switching the laser tube, an electric signal depending on the laser resonator temperature is measured and is compared with a supporting electric signal and upon the equality of both signals, the system for active thermoregulation of the resonator length of a frequency stabilized laser is switched. The electric signal depending on the laser resonator temperature is generated by the thermosensitive element that is mounted on the resonator.
A disadvantage of this known method for determining the moment of switching of the system for active thermoregulation of the resonator length of frequency stabilized lasers is that it reduced the reproducibility and increased the time for entering into the regime, because it does not take into consideration the impact of the ambient temperature at the moment of switching of the laser.
The last-mentioned device for determining the moment of switching of the system for active thermoregulation of resonator length of a frequency stabilized lasers comprises a comparator, the output of which is connected with the control input of the system for active thermoregulation of the resonator length of the frequency stabilized laser. Its first input is connected with a unit generating an electric signal depending on the laser resonator temperature. Its second input is connected with a source of a supporting or reference signal. The unit generating the electric signal depending on the laser resonator temperature is formed by a thermoresistance incorporated in a voltage divider. The thermoresistance is mounted on the laser tube.
A disadvantage of the known device for determining of the moment of switching of the system for active thermoregulation of the resonator length of frequency stabilized lasers is that the time for initialization of the frequency of laser radiation depends on the ambient temperature in the working site at the moment of switching of the laser because the device switches the system for active thermoregulation of the resonator length always at the same temperature of the laser resonator.